In the United States there are presently over 100,000 deaths per year resulting from bronchial carcinoma or lung cancer. Conventional treatments for lung cancer include surgery, radiation therapy and chemotherapy. Although the surgical removal of a malignant lung tissue remains as the effective method of choice of physicians, it may only be accomplished in a few early cases before intrathoracic or distant spread of the tumor has taken place. Radiation therapy by external beam has been found to be of limited value in prolonging the life of a patient with the disease even with doses in the range of 5,000 to 6,000 rads in view of the inability to control the irradiated tumor and a high incidence of distant metastases.
Interstitial irradiation has been shown to be promising for the local treatment of certain tumors assuming that the dose rate of radiation delivered from a stereotoxically implanted source is sufficiently high that tumor cells receive a critical threshold dose during a complete cell cycle. This condition can be met by using high-activity radioisotopes which can be removed from the site after the dose is delivered thereto. If the high-activity radioisotope were to remain implanted, normal tissue surrounding the radioactive source would be exposed to potentially toxic doses of radiation. It is known to utilize removable radioactive sources encased within catheters made to precisely hold the radioactive source at the tumor target site. An improvement in this art is disclosed in U.S. Pat. No. 4,584,991 to Tokita, et al.
In view of shortcomings presented by the present state of the radiation therapy art, applicant has developed an inventive implant capsule for radioisotopes which is adapted to be remotely implanted and retrieved by means of a catheter inserted through the collateral lumen of a fiberoptic bronchoscope. The capsule possesses resilient engaging means to enable the implant device to engage the bronchial walls when released at a predetermined location for treatment of a bronchial malignancy. The implant capsule has application to other organs and other types of endoscopes and may also be used for endoscopic drug delivery by placing a chemotherapeutic agent therein for localized or topical chemotherapy treatment.